A multi-shaft screw machine for preparing polymer melts is known from EP 2 374 601 A1. Strainer plates having a large number of through-openings for the polymer melt are arranged in the housing bores of the screw machine The polymer melt is conveyed through the through-openings. The polymer melt is divided here into a large number of part streams, so that the surface of the polymer melt is enlarged and the polymer melt is thereby degassed and homogenised.